You guys have got me confudled again cause you're mixing up yer terminoligy.
Are you talking about 'Mixdow' or 'Mastering'?

Mixdown is taking your 24, 48 (or whatever) track, and mixing it down to a 2 track master.

Mastering is taking that 2 track master and if necessary, applying EQ, Limiter and Compressor to get the optimum sound ready to go onto CD or Laquer.